PubMed Health⌕ Search

Biomedical subjects

R Rubio

Publications and source records attributed to R Rubio.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Regulation of coronary blood flow.

A very schematic summary of possible factors that affect coronary vascular resistance is illustrated in Fig. 11. These factors are mechanical, myogenic, metabolic, and neural. Mechanical influence is passive and is essentially determined by the extravascular compression which is important only during systole and particularly in the subendocardial layers of the left ventricular myocardium. With respect to the myogenic factor it is controversial whether it plays a role in adjustments of coronary vascular tone. Metabolic processes are possibly integrated at the level of the myocardial cell PO2 which is the resultant of oxygen supply and need, which in turn depend on the myocardial contractile activity as well as other biochemical processes. A decrease in myocardial PO2 gives rise to the release of the vasodilator metabolite adenosine. Nevertheless, other chemical factors (H+, K+, osmolarity) known to be released by the heart (which by themselves are poor and transient coronary vasodilators and whose release does not correspond with changes in coronary resistance) may play a role by modulating the coronary sensitivity to adenosine and other factors.

Adenosine↗
PubMedDate not supplied

Visceral leishmaniasis (kala-azar) as an opportunistic infection in patients infected with the human immunodeficiency virus in Spain.

In an area endemic for visceral leishmaniasis, 16 patients with human immunodeficiency virus (HIV) infection developed the disease. All belonged to populations at risk for AIDS (15 were intravenous drug abusers). Five patients fulfilled the criteria for full-blown AIDS, and two more fulfilled them after diagnosis of leishmaniasis. All presented with the classic manifestations of visceral leishmaniasis, but leishmania serology was negative in 15 patients (93%). Leishmania donovani amastigotes were identified in the bone marrow in all cases. Most patients responded initially to treatment with pentavalent antimonial drugs, but seven (43%) followed a chronic course, with multiple relapses in five, despite alternative treatments. Visceral leishmaniasis occurred in patients with different levels of depression of the CD4 to CD8 lymphocyte ratio. Mortality was 37% (six patients) and was independent of the chronic-relapsing course of the disease. In no case was leishmaniasis the primary cause of death. Our data establish that visceral leishmaniasis is an opportunistic infection in HIV-infected patients, and we suggest that in endemic areas it should be considered an indicator disease for the diagnosis of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Adenosine and metabolic regulation of coronary blood flow in dogs with renal hypertension.

It has been demonstrated that resting coronary vascular resistance is elevated with chronic hypertension and concomitant cardiac hypertrophy. The present study employed a model of 6-week, one-kidney, one wrapped Page hypertension to determine if the ability of the heart to match an increase in oxygen demand with an increase in oxygen supply (coronary blood flow) is impaired, and to determine if these vasoregulatory abnormalities are attributable to inadequate adenosine release. Studies were performed in a pentobarbital anesthetized, open-chest canine preparation using a pericardial infusate method to determine adenosine release. Results showed that dobutamine (a beta-receptor agonist) induced increases in myocardial oxygen consumption (MVO2) over a physiological range (8-30 ml O2 X min-1 X 100 g-1) that were accompanied by an increase in coronary blood flow (CBF) with no change in oxygen extraction. The relationship between MVO2 and CBF was not different between the normotensive (NTC) and hypertensive (RHT) animals. Pericardial infusate adenosine (PI ADO) concentrations were not different for the same MVO2 and CBF, and the relationships for MVO2 vs PI ADO as well as PI ADO vs CBF were unaltered by hypertension. However, the relationship between PI ADO and coronary vascular resistance (CVR) was altered in the RHT group such that a given PI ADO concentration was associated with a significantly higher CVR. These data suggest that, over the range of MVO2 studied, there are no limitations in metabolic regulation of the coronary circulation of RHT animals, and that the higher CVR encountered in the RHT group is not the result of a reduced release of the endogenous vasodilator, adenosine.

Adenosine↗
PubMedDate not supplied

Study of the validity of a questionnaire to assess the adherence to therapy in patients infected by HIV.

PURPOSE: The purpose of our study was to examine the validity of a questionnaire to detect nonadherence in HIV-infected patients under antiretroviral treatment. METHOD: This was a cross-sectional study to validate a diagnostic test. Participants consisting of 242 HIV-infected patients were elected by consecutive sampling in a hospital in Madrid. The validation standard was the pharmacy dispensing records with the cut point being 80% and 90% of delivered drugs. Sensitivity (S), specificity (SP), positive predictive value (PPV), and positive likelihood ratio (PLR) of the questionnaire were estimated. RESULTS: The mean age of the participants was 36.2 years old (SE 0.42), 55% were men, and 68.2% had used parenteral drugs. Eighty-three patients (34.3%) did not reach 80% of the prescribed dose and 129 patients (53.3%) did not reach 90%. In the 80% group, S was 25.3% (95% CI, 16.7%-36.2%),SP was 86.2% (95% CI, 79.6%-90.9%), PPV was 48.9% (95% CI, 33.5%-64.3%), and the PLR was 1.83 (95% CI, 1.07-3.13). In the 90% group, the S was 19.4% (95% CI, 13.4%-27.4%), SP was 84.0% (95% CI, 75.7%-90.0%), PPV was 58.1% (95% CI, 42.4%-72.6%), and PLR was 1.22 (95% CI, 0.70-2.12). CONCLUSION: The proposed questionnaire is not a reliable diagnostic method to detect nonadherence. It should only be incorporated into the daily clinical practice along with other methods of nonadherence measurement.

Adult↗